The present invention relates to apparatus and method for testing solid propellants and, more particularly, to a new and improved apparatus and method for testing solid propellants over a wide pressure range that is independent of the burning surface area of the propellant.
In previously used solid propellant test apparatus, the burning characteristics of the propellant have been tested under different pressures by varying the burning surface area of the propellant. While such test apparatus has performed satisfactorily, it has not been completely satisfactory in that it has only been possible to test the burning characteristics of the propellant over a limited number of pressures determined by the different burning surface areas of the propellant. A need has arisen, therefore, for a new and improved propellant test apparatus that is capable of testing solid propellants of different types over a wide pressure range independent of the burning surface area of the propellants. The test apparatus of the present invention fills this need.
The new and improved propellant test apparatus and method of the present invention provides a supplemental exhaust channel for the gases of the burning propellant being tested in addition to the normal or primary exhaust channel and exit nozzle at the end of the exhaust housing for the test apparatus. The flow of propellant gases through the supplemental exhaust channel is controlled by a valve of any suitable construction which can be controlled to vary the size of the supplemental exhaust channel over a wide range from fully open to fully closed. By varying the size of the supplemental exhaust channel, the flow of exhaust gases through the exit nozzle and the supplemental exhaust channel can be varied to control the combustion chamber pressure on the solid propellant being tested over a wide range that is independent of the burning surface area of the propellant. Accordingly, it is possible with the propellant test apparatus of the present invention to test the burning characteristics of different types of propellants over a wide pressure range that can be easily selectively controlled.